use std::ptr;

const NUM_TEST_VALUES: usize = 10000;

static mut test_array: [i32; NUM_TEST_VALUES] = [0; NUM_TEST_VALUES];

enum BinomialHeapType {
    Min,
    Max,
}

struct BinomialHeap {
    entries: Vec<i32>,
    heap_type: BinomialHeapType,
}

impl BinomialHeap {
    fn new(heap_type: BinomialHeapType, _compare: fn(i32, i32) -> i32) -> *mut BinomialHeap {
        let heap = Box::new(BinomialHeap {
            entries: Vec::new(),
            heap_type,
        });
        Box::into_raw(heap)
    }

    fn free(&mut self) {
        // Placeholder: In a real implementation, we would need to properly
        // deallocate all heap-allocated structures within the heap.
    }

    fn insert(&mut self, value: &i32) -> bool {
        self.entries.push(*value);
        true
    }

    fn num_entries(&self) -> usize {
        self.entries.len()
    }

    fn pop(&mut self) -> *mut i32 {
        if self.entries.is_empty() {
            ptr::null_mut()
        } else {
            let val = self.entries.remove(0);
            Box::into_raw(Box::new(val))
        }
    }
}

fn int_compare(a: i32, b: i32) -> i32 {
    a.cmp(&b) as i32
}

fn alloc_test_set_limit(_limit: isize) {
    // Placeholder: In a real implementation, we would set a memory allocation limit.
}

fn test_binomial_heap_new_free() {
    let mut heap: *mut BinomialHeap;
    for _ in 0..NUM_TEST_VALUES {
        unsafe {
            heap = BinomialHeap::new(BinomialHeapType::Min, int_compare);
            (*heap).free();
        }
    }

    unsafe {
        alloc_test_set_limit(0);
        assert!(BinomialHeap::new(BinomialHeapType::Min, int_compare).is_null());
    }
}

fn test_binomial_heap_insert() {
    let mut heap: *mut BinomialHeap;
    unsafe {
        heap = BinomialHeap::new(BinomialHeapType::Min, int_compare);

        for i in 0..NUM_TEST_VALUES {
            test_array[i] = i as i32;
            assert!((*heap).insert(&test_array[i]));
        }
        assert_eq!((*heap).num_entries(), NUM_TEST_VALUES);

        alloc_test_set_limit(0);
        assert!(!(*heap).insert(&0));

        (*heap).free();
    }
}

fn test_min_heap() {
    let mut heap: *mut BinomialHeap;
    let mut val: *mut i32;
    unsafe {
        heap = BinomialHeap::new(BinomialHeapType::Min, int_compare);

        for i in 0..NUM_TEST_VALUES {
            test_array[i] = i as i32;
            assert!((*heap).insert(&test_array[i]));
        }

        for i in 0..NUM_TEST_VALUES {
            val = (*heap).pop();
            assert_eq!(*val, i as i32);
            drop(Box::from_raw(val));
        }

        val = (*heap).pop();
        assert!(val.is_null());

        (*heap).free();
    }
}

fn test_max_heap() {
    let mut heap: *mut BinomialHeap;
    let mut val: *mut i32;
    unsafe {
        heap = BinomialHeap::new(BinomialHeapType::Max, int_compare);

        for i in 0..NUM_TEST_VALUES {
            test_array[i] = i as i32;
            assert!((*heap).insert(&test_array[i]));
        }

        for i in (0..NUM_TEST_VALUES).rev() {
            val = (*heap).pop();
            assert_eq!(*val, i as i32);
            drop(Box::from_raw(val));
        }

        val = (*heap).pop();
        assert!(val.is_null());

        (*heap).free();
    }
}

const TEST_VALUE: usize = NUM_TEST_VALUES / 2;

unsafe fn generate_heap() -> *mut BinomialHeap {
    let mut heap = BinomialHeap::new(BinomialHeapType::Min, int_compare);

    for i in 0..NUM_TEST_VALUES {
        test_array[i] = i as i32;
        if i != TEST_VALUE {
            assert!(heap.as_mut().unwrap().insert(&test_array[i]));
        }
    }

    heap
}

unsafe fn verify_heap(heap: *mut BinomialHeap) {
    let mut num_vals = (*heap).num_entries();
    assert_eq!(num_vals, NUM_TEST_VALUES - 1);

    for i in 0..NUM_TEST_VALUES {
        if i == TEST_VALUE {
            continue;
        }

        let val = (*heap).pop();
        assert_eq!(*val, i as i32);
        drop(Box::from_raw(val));

        num_vals -= 1;
        assert_eq!((*heap).num_entries(), num_vals);
    }
}

fn test_insert_out_of_memory() {
    let mut heap: *mut BinomialHeap;
    unsafe {
        for i in 0..6 {
            heap = generate_heap();

            alloc_test_set_limit(i);
            test_array[TEST_VALUE] = TEST_VALUE as i32;
            assert!(!(*heap).insert(&test_array[TEST_VALUE]));
            alloc_test_set_limit(-1);

            verify_heap(heap);

            (*heap).free();
        }
    }
}

fn test_pop_out_of_memory() {
    let mut heap: *mut BinomialHeap;
    unsafe {
        for i in 0..6 {
            heap = generate_heap();

            alloc_test_set_limit(i);
            assert!((*heap).pop().is_null());
            alloc_test_set_limit(-1);

            (*heap).free();
        }
    }
}

fn main() {
    let tests: &[fn()] = &[
        test_binomial_heap_new_free,
        test_binomial_heap_insert,
        test_min_heap,
        test_max_heap,
        test_insert_out_of_memory,
        test_pop_out_of_memory,
    ];

    for test in tests {
        test();
    }
}